Prepare the oven: Heat oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.
Mix dry ingredients: Whisk flour, pumpkin pie spice, baking powder, baking soda, and salt in a bowl.
Make the batter: In another bowl, whisk pumpkin, brown sugar, eggs, oil, and vanilla. Gently fold in the dry ingredients until just combined.
Bake: Divide batter between liners, filling each about two-thirds full. Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean. Cool completely.
Make frosting: Beat softened butter until creamy. Add cream cheese and beat until smooth. Gradually mix in powdered sugar and vanilla until fluffy.
Decorate: Pipe frosting onto cooled cupcakes and finish with Halloween sprinkles, candy pumpkins, edible eyes, or other decorations. Serve and enjoy!